Xenbase
- Collection of information on early amphibian development, methods including immunohistochemistry, in situ hybridization, molecular markers, based on Xenopus, as part of the WWW Virtual Library.
- http://www.xenbase.org/

Amphibian Embryology Tutorial
- Glossary and graphical illustration of oogenesis, cleavage, gastrulation and neuraltion, primarily in Ambystoma and Xenopus, from the University of Wisconsin, Madison.
- http://worms.zoology.wisc.edu/frogs/mainmenu.html